There was old identi.ca, which was scrapped (I know more
polite term is "moved to GNU/Social", yeah … how many users of
this social software there is? And yes, I know, the protocol
is named differently, but it is just another version of the
same thing from my point of view), and pump.io, which is … I
have just upgraded my instance to see whether I can write
honestly that it is a well working proprietary (meaning, used
by one implementation by the author of the protocol only)
distributed network, and no, it is broken.

And even if the damned thing worked, it would not offer me the
functionality I really want: which is to connect with my real
friends, who are all on Twitter, Facebook, or even some on G+.
Heck, pump.io would be useless even these friends were on
Diaspora (no, they are not, nobody is there). So, yes, if you
want something which is useless, go and write OStatus
component.